<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>计算器示例</title>
    <link rel="stylesheet" href="../plugins/bootstrap-4.5.3-dist/css/bootstrap.min.css">
    <script src="../plugins/jquery/jquery-3.5.1.min.js"></script>
    <script src="../plugins/bootstrap-4.5.3-dist/js/bootstrap.min.js"></script>
</head>
<body>

    <div class="container" style="margin-top: 50px;width: 600px">
        <div class="row">
            <input class="col form-control" style="height: 50px"/>
        </div>
        <div class="row">
            <div class="col">
                <button type="button" class="btn btn-info">1</button>
            </div>
            <div class="col">
                <button type="button" class="btn btn-info">2</button>
            </div>
            <div class="col">
                <button type="button" class="btn btn-info">3</button>
            </div>
            <div class="col">
                <button type="button" class="btn btn-warning">+</button>
            </div>
        </div>
        <div class="row">
            <div class="col">
                <button type="button" class="btn btn-info">4</button>
            </div>
            <div class="col">
                <button type="button" class="btn btn-info">5</button>
            </div>
            <div class="col">
                <button type="button" class="btn btn-info">6</button>
            </div>
            <div class="col">
                <button type="button" class="btn btn-warning">-</button>
            </div>
        </div>
        <div class="row">
            <div class="col">
                <button type="button" class="btn btn-info">7</button>
            </div>
            <div class="col">
                <button type="button" class="btn btn-info">8</button>
            </div>
            <div class="col">
                <button type="button" class="btn btn-info">9</button>
            </div>
            <div class="col">
                <button type="button" class="btn btn-warning">*</button>
            </div>
        </div>
        <div class="row">
            <div class="col">
                <button type="button" class="btn btn-danger">CE</button>
            </div>
            <div class="col">
                <button type="button" class="btn btn-info">0</button>
            </div>
            <div class="col">
                <button type="button" class="btn btn-success">=</button>
            </div>
            <div class="col">
                <button type="button" class="btn btn-warning">/</button>
            </div>
        </div>
    </div>
</body>
<style>
    div{
        margin-top: 10px;
    }
    .btn{
        padding: 0;
        margin: 0;
        font-size: 4rem;
        font-weight: bolder;
        min-width: 100px;
        min-height: 100px;
        line-height: 100px;
        text-align: center;
    }
</style>
</html>